I don't agree. Olympic wrestling is one of the most intense environments for competition. He dominated international competition for thirteen years against a much wider pool of potential opponents than Roger ever will. And beat them soundly. There is also some debate on the topic but most folks agree that Karelin had at least some sambo experience.
Again, I have to disagree. Without a gi Karelin would throw his opponents like they had never been thrown before. Compare it to a wrestler who has occasionally done submissions with his friend suddenly walking into a BJJ school and fighting a brown belt. That would be the difference in the power of his throws and the BJJ player's ability to defend them. A man who could throw dedicated Greco-Roman Olympians as easily as Karelin could plaster your average BJJ black belt in nogi standing with vicious throws.
In the gi, the fight would be much more competitive and I think that if a good player could jump guard there is a good chance they could secure a gi choke due simply to Karelin's submission inexperience. It's the same reason he would throw them in nogi, because he does something they barely do better than anyone else in the world does. Against roger in gi he would barely know the techniques of Roger, who is also the best in the world at what he does.
I'm not sure if you were using this post to refute my statements or just to contribute to the thread. If it's the latter, I apologize. If it's the former, I just don't think Karelin is the kind of guy you want to compare resumes against.